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Almarudite

A valid IMA mineral species

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Almarudite

Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany

Almarudite

Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany

Almarudite

Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany

Almarudite

Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany

Almarudite

Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany

Almarudite

Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany

Almarudite

Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany

Almarudite

Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany

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About AlmaruditeHide

Seal of the University of Vienna

Formula:

K◻₂Mn²⁺₂(Be₂Al)[Si₁₂O₃₀]

some Na reported in the B site (dominated by ◻ in the end-member formula);
some Mg and Fe reported in the A site (dominated by Mn in the end-member formula)

Colour:

Yellow to orange

Lustre:

Vitreous

Hardness:

Specific Gravity:

2.714 (Calculated)

Crystal System:

Hexagonal

Member of:

Osumilite Group

Name:

For the University of Vienna, Austria (in latin: ALma MAter RUDolphina).

Type Locality:

ⓘ Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany

Osumilite Group.
Calcium- and water-free analogue of milarite.

Can be distinguished from its Mg analogue friedrichbeckeite and yellowish roedderite only by quantitative chemical analysis.

Unique IdentifiersHide

Mindat ID:

25681

Long-form identifier:

mindat:1:1:25681:8

IMA Classification of AlmaruditeHide

IMA status:

Approved

IMA Formula:

K(◻,Na)₂(Mn²⁺,Fe²⁺,Mg)₂[(Be,Al)₃Si₁₂]O₃₀

Approval year:

2002

First published:

2004

Classification of AlmaruditeHide

Strunz-mindat (2026):

9.CM.05

9 : SILICATES (Germanates)
C : Cyclosilicates
M : [Si₆O₁₈]₁₂- 6-membered double rings (sechser-Doppelringe)

Mineral SymbolsHide

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.

Symbol	Source	Reference for Standard
Alr	IMA–CNMNC	Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43
Alr	The Canadian Mineralogist (2019)	The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download

Physical Properties of AlmaruditeHide

Lustre:

Vitreous

Transparency:

Transparent, Translucent

Colour:

Yellow to orange

Streak:

Pale orange

Hardness:

6 on Mohs scale

Tenacity:

Brittle

Cleavage:

None Observed

Fracture:

Irregular/Uneven

Density:

2.714 g/cm³ (Calculated)

Optical Data of AlmaruditeHide

Type:

Uniaxial (-)

RI values:

n_ω = 1.560(1) n_ε = 1.559(1)

Max. Birefringence:

δ = 0.001
Based on recorded range of RI values above.

Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.

Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.

Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.

Thickness: 30 µm Order divisions

Rotation:

Surface Relief:

Low (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).

This shows the grain boundary and Becke line effect under plane-polarised light, based on the contrast between this mineral's average refractive index and the mounting medium. It does not take into account mineral colouration.

Focus:

In focus

Interference Figure:

This shows the idealized uniaxial interference figure - the conoscopic (convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis centred and vertical. The coloured rings are isochromatics, computed with the same physics as the Michel-Lévy bar above; the dark cross is the isogyre.

For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.

Thickness: 30 µm

Optical Extinction:

Anomalous extinction, biaxial optics, and zoning are common.

Pleochroism:

Strong

Comments:

O = orange, E = colorless.

Chemistry of AlmaruditeHide

Mindat Formula:

K◻₂Mn²⁺₂(Be₂Al)[Si₁₂O₃₀]

some Na reported in the B site (dominated by ◻ in the end-member formula);
some Mg and Fe reported in the A site (dominated by Mn in the end-member formula)

Element Weights:

Element	% weight
O	47.477 %
Si	33.336 %
Mn	10.868 %
K	3.867 %
Al	2.669 %
Be	1.783 %

Calculated from ideal end-member formula.

Elements listed:

Al, Be, K, Mn, O, Si - search for minerals with similar chemistry

Common Impurities:

Na,Fe,Mg

Crystallography of AlmaruditeHide

Crystal System:

Hexagonal

Class (H-M):

6/mmm(6/m2/m2/m) - Dihexagonal Dipyramidal

Space Group:

P6/mmm

Cell Parameters:

a = 9.997(1) Å, c = 14.090(1) Å

Ratio:

a:c = 1 : 1.409

Unit Cell V:

1,219.50 Å³ (Calculated from Unit Cell)

Morphology:

Tabular crystals, flattened on {0001}.
Forms include {0001}, {1010}, {1012}, {1120}.

Crystal StructureHide

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Unit Cell | Unit Cell Packed
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure

ID	Species	Reference	Link	Year	Locality	Pressure (GPa)	Temp (K)
0014724	Almarudite	Mihajlovic T, Lengauer C L, Ntaflos T, Lolitsch U, Tillmanns E (2004) Two new minerals, rondorfite, Ca8Mg[SiO4]4Cl2, and almarudite, K(box,Na)2(Mn,Fe,Mg)2(Be,Al)3[Si12O30], and a study of iron-rich wadalite, Ca12[(Al8Si4Fe2)O32]C16, from the Bellerberg (Bellberg) volcano, Eifel, Germany Eastern Eifel volcanic area, Eifel, Germany Neues Jahrbuch fur Mineralogie, Abhandlungen 179 265-294		2004	Bellerberg volcano lava field, 2 km N of Mayen,	0	293

CIF Raw Data - click here to close

data_global
_chemical_name_mineral 'Almarudite'
loop_
_publ_author_name
'Mihajlovic T'
'Lengauer C L'
'Ntaflos T'
'Lolitsch U'
'Tillmanns E'
_journal_name_full 'Neues Jahrbuch fur Mineralogie, Abhandlungen'
_journal_volume 179 
_journal_year 2004
_journal_page_first 265
_journal_page_last 294
_publ_section_title
;
 Two new minerals, rondorfite, Ca8Mg[SiO4]4Cl2, and almarudite,
 K(box,Na)2(Mn,Fe,Mg)2(Be,Al)3[Si12O30], and a study of iron-rich wadalite,
 Ca12[(Al8Si4Fe2)O32]C16, from the Bellerberg (Bellberg) volcano, Eifel, Germany
 Eastern Eifel volcanic area, Eifel, Germany
;
_database_code_amcsd 0014724
_chemical_compound_source 'Bellerberg volcano lava field, 2 km N of Mayen,'
_chemical_formula_sum 'K.928 Na.2 (Mn1.058 Fe.62 Mg.322) (Be2.214 Al.786) Si12 O30'
_cell_length_a 9.997
_cell_length_b 9.997
_cell_length_c 14.090
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120
_cell_volume 1219.498
_exptl_crystal_density_diffrn      2.722
_symmetry_space_group_name_H-M 'P 6/m c c'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  '-x,-x+y,1/2+z'
  'x,x-y,1/2-z'
  '-x+y,-x,-z'
  'x-y,x,z'
  '-y,-x,1/2+z'
  'y,x,1/2-z'
  'y,-x+y,-z'
  '-y,x-y,z'
  'x-y,-y,1/2+z'
  '-x+y,y,1/2-z'
  'x,y,-z'
  '-x,-y,z'
  'x,x-y,1/2+z'
  '-x,-x+y,1/2-z'
  'x-y,x,-z'
  '-x+y,-x,z'
  'y,x,1/2+z'
  '-y,-x,1/2-z'
  '-y,x-y,-z'
  'y,-x+y,z'
  '-x+y,y,1/2+z'
  'x-y,-y,1/2-z'
  '-x,-y,-z'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_U_iso_or_equiv
KA   0.00000   0.00000   0.25000   0.92800   0.02510
NaB   0.33333   0.66667   0.02500   0.05000   0.00900
MnM   0.33333   0.66667   0.25000   0.52900   0.01060
FeM   0.33333   0.66667   0.25000   0.31000   0.01060
MgM   0.33333   0.66667   0.25000   0.16100   0.01060
BeT2   0.50000   0.00000   0.25000   0.73800   0.01140
AlT2   0.50000   0.00000   0.25000   0.26200   0.01140
SiT1   0.09503   0.35169   0.10857   1.00000   0.00850
O1   0.11300   0.40890   0.00000   1.00000   0.02210
O2   0.20770   0.28270   0.12747   1.00000   0.02410
O3   0.12912   0.48752   0.18076   1.00000   0.01500
loop_
_atom_site_aniso_label
_atom_site_aniso_U_11
_atom_site_aniso_U_22
_atom_site_aniso_U_33
_atom_site_aniso_U_12
_atom_site_aniso_U_13
_atom_site_aniso_U_23
KA 0.02430 0.02430 0.02680 0.01220 0.00000 0.00000
NaB 0.00200 0.00200 0.02000 0.00100 0.00000 0.00000
MnM 0.01090 0.01090 0.00990 0.00550 0.00000 0.00000
FeM 0.01090 0.01090 0.00990 0.00550 0.00000 0.00000
MgM 0.01090 0.01090 0.00990 0.00550 0.00000 0.00000
BeT2 0.01300 0.01040 0.00990 0.00650 0.00000 0.00000
AlT2 0.01300 0.01040 0.00990 0.00650 0.00000 0.00000
SiT1 0.00900 0.01040 0.00660 0.00521 -0.00035 -0.00154
O1 0.03730 0.02060 0.00740 0.01380 0.00000 0.00000
O2 0.02730 0.03730 0.02160 0.02650 -0.00360 -0.00640
O3 0.02360 0.01560 0.01050 0.01320 -0.00280 -0.00400

X-Ray Powder DiffractionHide

Powder Diffraction Data:

d-spacing	Intensity
7.047 Å	(40)
5.467 Å	(25)
5.000 Å	(40)
4.331 Å	(30)
4.076 Å	(80)
3.691 Å	(25)
3.522 Å	(40)
3.266 Å	(30)
3.187 Å	(100)
3.967 Å	(5)
2.882 Å	(100)
2.732 Å	(50)
2.687 Å	(30)
2.498 Å	(20)
2.400 Å	(20)
2.365 Å	(20)
2.139 Å	(15)
1.983 Å	(30)
1.890 Å	(15)
1.873 Å	(15)
1.826 Å	(40)
1.762 Å	(5)
1.712 Å	(20)
1.665 Å	(20)
1.569 Å	(5)
1.506 Å	(30)
1.440 Å	(15)
1.414 Å	(30)
1.386 Å	(10)
1.356 Å	(10)
1.335 Å	(10)
1.312 Å	(30)
1.195 Å	(30)
1.178 Å	(10)
1.089 Å	(20)

Locality:

Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany

Comments:

Mihajlovic, T., Lengauer, C.L., Ntaflos, Th., Kolitsch, U., Tillmanns, E. (2004): Two new minerals, rondorfite, Ca8Mg[SiO4]4Cl2, and almarudite, K(,Na,)2(Mn,Fe,Mg)2(Be,Al)3[Si12O30], and a study of iron-rich wadalite, Ca12[(Al8Si4Fe2)O32]Cl6, from the Bellerberg volcano, Eifel, Germany, N. Jb. Miner. Abh. 179, 265-294.

Geological EnvironmentHide

Paragenetic Mode(s):

Paragenetic Mode	Earliest Age (Ga)
High-? alteration and/or metamorphism
31 : Thermally altered carbonate, phosphate, and iron formations

Type Occurrence of AlmaruditeHide

Type Locality:

ⓘ Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany

General Appearance of Type Material:

Euhedral, tabular crystals to 1.5 mm across and 0.2 mm thick.

Place of Conservation of Type Material:

The Natural History Museum, Vienna, Austria.

Geological Setting of Type Material:

In vugs of siliceous xenolites in leucite-rich lava slags.

Associated Minerals at Type Locality:

Amphibole Supergroup	Braunite	Clinopyroxene Subgroup	Hematite	Quartz
Sanidine	Sillimanite	Tridymite

Synonyms of AlmaruditeHide

IMA2002-048

Other Language Names for AlmaruditeHide

Dutch:Almarudiet

French:Almarudite

German:Almarudit

Norwegian:Almaruditt

Simplified Chinese:阿尔玛鲁道夫石

Traditional Chinese:阿爾瑪魯道夫石

Relationship of Almarudite to other SpeciesHide

Member of:

Osumilite Group

Other Members of Osumilite Group:

Agakhanovite-(Y)	K◻₂(YCa)Be₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Aluminosugilite	KNa₂Al₂Li₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Armenite	Ba(H₂O)₂Ca₂Al₃[Al₃Si₉O₃₀]	Orth. mmm(2/m2/m2/m) : Pnna
Berezanskite	K◻₂Ti₂Li₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Brannockite	K◻₂Sn₂Li₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Chayesite	K◻₂Mg₂(Mg₂Fe³⁺)[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Darapiosite	KNa₂Mn₂(Zn₂Li)[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Dusmatovite	K(K◻)Mn²⁺₂Zn₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Eifelite	KNa₂(MgNa)Mg₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Friedrichbeckeite	K(◻Na)Mg₂(Be₂Mg)[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Klöchite	K◻₂(Fe²⁺Fe³⁺)Zn₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6₃/mmc
Laurentthomasite	K◻₂Mg₂(Be₂Al)[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Merrihueite	K(◻Na)Fe²⁺₂Fe²⁺₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Milarite	K(◻H₂O)Ca₂(Be₂Al)[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Oftedalite	K◻₂(ScCa)Be₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Osumilite	K◻₂Fe²⁺₂Al₃[Al₂Si₁₀O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Osumilite-(Mg)	K◻₂Mg₂Al₃[Al₂Si₁₀O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Plechovite	Ca₂[K(H₂O)]KBe₃Si₁₂O₃₀	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Poudretteite	K◻₂Na₂B₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Roedderite	K(◻Na)Mg₂Mg₃[Si₁₂O₃₀]	Hex. 6m2 : P62c
Shibkovite	K(◻K)Ca₂Zn₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Sogdianite	K◻₂Zr₂Li₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Sugilite	KNa₂Fe³⁺₂Li₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
Trattnerite	◻(◻)₂Fe³⁺₂Mg₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
'UM1990-73-SiO:KMnNaZn'	K(KNa_0.5◻_0.5)(Mn_1.5Na_0.5)Zn₃[Si₁₂O₃₀]	Hex.
'Unnamed (Mn3+-dominant analog of Sugilite)'	KNa₂Mn³⁺₂Li₃[Si₁₂O₃₀]
Yagiite	Na◻₂Mg₂Al₃[Al₂Si₁₀O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc

Common AssociatesHide

Associations Based on Photo Data:

1 photo of Almarudite associated with Pyroxene Group

ADSi₂O₆

Related Minerals - Strunz-mindat Grouping Hide

9.CM.	Agakhanovite-(Y)	K◻₂(YCa)Be₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.	Plechovite	Ca₂[K(H₂O)]KBe₃Si₁₂O₃₀	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Friedrichbeckeite	K(◻Na)Mg₂(Be₂Mg)[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Laurentthomasite	K◻₂Mg₂(Be₂Al)[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	'UM1990-73-SiO:KMnNaZn'	K(KNa_0.5◻_0.5)(Mn_1.5Na_0.5)Zn₃[Si₁₂O₃₀]	Hex.
9.CM.05	Eifelite	KNa₂(MgNa)Mg₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Armenite	Ba(H₂O)₂Ca₂Al₃[Al₃Si₉O₃₀]	Orth. mmm(2/m2/m2/m) : Pnna
9.CM.05	Merrihueite	K(◻Na)Fe²⁺₂Fe²⁺₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Oftedalite	K◻₂(ScCa)Be₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Roedderite	K(◻Na)Mg₂Mg₃[Si₁₂O₃₀]	Hex. 6m2 : P62c
9.CM.05	Shibkovite	K(◻K)Ca₂Zn₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Sogdianite	K◻₂Zr₂Li₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Milarite	K(◻H₂O)Ca₂(Be₂Al)[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Berezanskite	K◻₂Ti₂Li₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Poudretteite	K◻₂Na₂B₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Darapiosite	KNa₂Mn₂(Zn₂Li)[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Chayesite	K◻₂Mg₂(Mg₂Fe³⁺)[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Osumilite-(Mg)	K◻₂Mg₂Al₃[Al₂Si₁₀O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Osumilite	K◻₂Fe²⁺₂Al₃[Al₂Si₁₀O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Sugilite	KNa₂Fe³⁺₂Li₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Trattnerite	◻(◻)₂Fe³⁺₂Mg₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Brannockite	K◻₂Sn₂Li₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Klöchite	K◻₂(Fe²⁺Fe³⁺)Zn₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6₃/mmc
9.CM.05	Dusmatovite	K(K◻)Mn²⁺₂Zn₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.05	Yagiite	Na◻₂Mg₂Al₃[Al₂Si₁₀O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.9.CM.	Aluminosugilite	KNa₂Al₂Li₃[Si₁₂O₃₀]	Hex. 6/mmm(6/m2/m2/m) : P6/mcc
9.CM.10	Faizievite	K₂Na(Ca₆Na)Ti₄Li₆[Si₆O₁₈]₂[Si₁₂O₃₀]F₂	Tric. 1 : P1

RadioactivityHide

Radioactivity:

Element	% Content	Activity (Bq/kg)	Radiation Type
Uranium (U)	0.0000%	0	α, β, γ
Thorium (Th)	0.0000%	0	α, β, γ
Potassium (K)	3.8673%	1,199	β, γ

For comparison:

Banana: ~15 Bq per fruit
Granite: 1,000–3,000 Bq/kg
EU exemption limit: 10,000 Bq/kg

Note: Risk is shown relative to daily recommended maximum exposure to non-background radiation of 1000 µSv/year. Note that natural background radiation averages around 2400 µSv/year so in reality these risks are probably extremely overstated! With infrequent handling and safe storage natural radioactive minerals do not usually pose much risk.

Interactive Simulator:

Note: The mass selector refers to the mass of radioactive mineral present, not the full specimen, also be aware that the matrix may also be radioactive, possibly more radioactive than this mineral!

Mass of radioactive mineral:

Shielding material:

Activity: –

Distance	Dose rate	Risk
1 cm
10 cm
1 m

The external dose rate (D) from a radioactive mineral is estimated by summing the gamma radiation contributions from its Uranium, Thorium, and Potassium content, disregarding daughter-product which may have a significant effect in some cases (eg 'pitchblende'). This involves multiplying the activity (A, in Bq) of each element by its specific gamma ray constant (Γ), which accounts for its unique gamma emissions. The total unshielded dose at 1 cm is then scaled by the square of the distance (r, in cm) and multiplied by a shielding factor (μ_shield). This calculation provides a 'worst-case' or 'maximum risk' estimate because it assumes the sample is a point source and entirely neglects any self-shielding where radiation is absorbed within the mineral itself, meaning actual doses will typically be lower. The resulting dose rate (D) is expressed in microsieverts per hour (μSv/h).

D = ((A_U × Γ_U) + (A_Th × Γ_Th) + (A_K × Γ_K)) / r² × μ_shield

Fluorescence of AlmaruditeHide

In UV light:

none

Other InformationHide

Health Risks:

No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Internet Links for AlmaruditeHide

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https://www.mindat.org/min-25681.html
Please feel free to link to this page.

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External Links:

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Raman and XRD data at RRUFF project

References and PDF downloads at RRUFF project

American Mineralogist Crystal Structure Database

Handbook of Mineralogy page PDF

Mineral Dealers:

Buy from D. Joyce minerals

References for AlmaruditeHide

Reference List:

Mihajlović, Tamara, Lengauer, Christian L., Ntaflos, Theodoros, Kolitsch, Uwe, Tillmanns, Ekkehart (2004) Two new minerals, rondorfite, Ca₈Mg[SiO₄]₄Cl₂, and almarudite, K(□,Na)₂(Mn,Fe,Mg)₂(Be,Al)₃[Si₁₂O₃₀], and a study of iron-rich wadalite, Ca₁₂[(Al₈Si₄Fe₂)O₃₂]Cl₆, from the Bellerberg (Bellberg) volcano, Eifel, Germany. Neues Jahrbuch für Mineralogie - Abhandlungen, 179 (3). 265-294 doi:10.1127/0077-7757/2004/0179-0265

Jambor, John L.; Grew, Edward J.; Roberts, Andrew C. (2004) New Mineral Names. American Mineralogist, 89 (10). 1574-1578

Mandarino, Joseph A. (2004) New minerals. The Canadian Mineralogist, 42 (4) 1241-1260 doi:10.2113/gscanmin.42.4.1241

Lapis 29(3), 39 (2004).

Rondorf, A. & Rondorf, E. (2008): Almarudit vom Bellerberg/Eifel. Mineralien-Welt 19 (5), 4.

(2021) Almarudite. Handbook of Mineralogy. Mineralogical Society of America

Localities for AlmaruditeHide

Showing 2 localities.

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the

symbol to view information about a locality. The

symbol next to localities in the list can be used to jump to that position on the map.

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Locality ListHide

- This locality has map coordinates listed.

- This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality.

- Good crystals or important locality for species.

- World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). ~~Struck out~~ - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.


Germany (TL)
Rhineland-Palatinate Mayen-Koblenz Vordereifel Ettringen ⓘ Caspar quarry (TL)	Mihajlović et al. (2004) +1 other reference

Spain
Canary Islands Santa Cruz de Tenerife Province Tenerife ⓘ ~~Playa de San Juan~~	Dill et al. (2023)

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Almarudite

About AlmaruditeHide

Unique IdentifiersHide

IMA Classification of AlmaruditeHide

Classification of AlmaruditeHide

Mineral SymbolsHide

Physical Properties of AlmaruditeHide

Optical Data of AlmaruditeHide

Chemistry of AlmaruditeHide

Crystallography of AlmaruditeHide

Crystal StructureHide

X-Ray Powder DiffractionHide

Geological EnvironmentHide

Type Occurrence of AlmaruditeHide

Synonyms of AlmaruditeHide

Other Language Names for AlmaruditeHide

Relationship of Almarudite to other SpeciesHide

Common AssociatesHide

Related Minerals - Strunz-mindat GroupingHide

RadioactivityHide

Fluorescence of AlmaruditeHide

Other InformationHide

Internet Links for AlmaruditeHide

References for AlmaruditeHide

Localities for AlmaruditeHide

Locality ListHide

Related Minerals - Strunz-mindat Grouping Hide